Transceiver modules, such as optical to electrical transceiver modules, are available in standardized packages and form factors. These standardized modules, in form factors such as XENPAK, XPAK, and/or X2, allow manufacturers of digital networking equipment such as switches, hubs, and routers to provide for field replaceable and upgradeable interfaces between the network device and external data lines. Typical modules of is type are sold by Cisco, Finisar, JDS Uniphase, Avago Technologies, and Intel to name but a few companies.
These modules typically contain not only the transceiver, which comprises an optical receiver—preamplifier and a laser diode transmitter, but also additional circuitry for data encoding and decoding, diagnostics, serial numbers and manufacturer identification, power control, and the like.
Since the electro-optical elements are built into the module, a different module must be designed, tested, and manufactured for each optical solution, such as 850 nm, 1310 nm, 1550 nm wavelengths, different laser power levels, different optical connectors, and so on. For every change or innovation in the optical portion, a complete new module is needed